The present invention relates generally to an automotive automatic air conditioning system which automatically controls system operation according to predetermined mode switching parameters. More particularly, the invention relates to a mode selecting procedure in an automatic air conditioning system for an automotive vehicle.
Under automatic control, air outlets discharging conditioned air are selected to be open or closed according to the selected operational mode and in accordance with the open-degree of an air-mix door. Conventionally, one of the per se well-known VENT, BI-LEVEL, and HEATER modes is selected depending upon the air-mix door open ratio. In such conventional air-mix door open-degree-dependent mode selection procedures, it is possible that the selected operational mode will not precisely correspond to other air conditioning parameters. For instance, the temperature of the discharged air at a given air-mix door open-degree is not always the same and in fact will vary according to various temperature-influencing factors such as ambient temperature and insolation. Furthermore, different occupants in the passenger compartment may subjectively feel hot or cold even at substantially the same compartment temperature and/or at the same conditioned air temperature. Such subjective tastes sometimes engender selection of an operational mode different from that selected with regard solely to air-mix door open-degree.